Hitch pin for stringed instruments



H. A. CONKLIN, JR

HITCH PIN FOR STRINGED INSTRUMENTS Filed Aug. 15, 1966 INVENTOR United States Patent O 3,478,635 HITCH PIN FOR STRINGED INSTRUMENTS Harold A. Conklin, Jr., Cincinnati, Ohio, assignor to D. H. Baldwin Company, Cincinnati, Ohio, a corporation of Ohio Filed Aug. 15, 1966, Ser. No. 572,496 Int. Cl. G10c 3/04, 3/08, 3/10 U.S. Cl. 84-197 ABSTRACT OF THE DISCLOSURE A stringed musical instrument wherein the strings are secured at their rear ends to smooth cylindrical hitch pins having their axes substantially normal to the string plate and to the direction of extent of the strings, the strings engaging the hitch pins at points spaced upwardly from the string plate and being movable vertically to adjust the downbearing of the strings on the bridge of the instrument with which the strings are associated, the hitch pins preferably being in the form of hollow cylindrical members having a longitudinal split ther-ein, the pins being spaced from the bridge of the piano in accordance with a prearranged schedule so that the length of the strings extending between the pins and the bridge will bear a substantially harmonic relationship to the speaking lengths of the strings.

The invention relates to stringed instruments and has to do more particularly with an improved hitch pin construction by means of which the bearing of the strings on the bridge or equivalent structure of the instrument may be readily adjusted. While its utility is not so limited, the invention will be described as it applies to a grand piano. Such piano is characterized by a horizontal string plate, a soundboard located beneath the string plate, a keyboard, and an upwardly operating action, the hammers of which strike the strings from beneath.

A basic object of the invention is the provision of improvements in the construction of the hitch pins of such pianos as will facilitate the adjustment of the strings and improve the tonal characteristics of the instrument.

Ancillary objects of the invention may be set forth as follows:

It is an object of the invention to provide a hitch pin structure acting to conserve the energy imparted to the strings by the operation of the hammers so as to achieve a conservation of energy in the duplex section to the strings, i.e., the portion of the strings extending between the bridge or its equivalent and the hitch pins.

It is an object of the invention to provide a hitch pin type of string termination which is simpler and less expensive than comparable structures heretofore used.

It is an object of the invention to provide a way in which the bearing force exerted upon the bridge of the instrument by the strings can be more elfectively controlled to establish the desired downbearing on the bridge vand soundboard when the strings are at rest.

These and other objects of the invention which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these specications, are accomplished by those features of construction of which certain exemplary embodiments will now be described.

FIGURE 1 is a partial plan view of a grand piano case and string frame.

FIGURE 2 is a partial sectional view taken along a string or string assembly showing the bridge, part of the soundboard and an edge portion of the plate having means for forming the rear termination of a string or strings.

s claims` ice .erence is first made to FIGURE l. The conventional piano case has an outer rim 1 of substantial depth and an inner rim 2 of lesser depth. A soundboard 3 is mounted to the inner rim and to a transverse frame member 4 forming a part of the piano case. A string plate 5 is mounted on the inner rim within the piano case. The

plate may take various forms; but a typical one is shown in FIGURE 1. It has peripheral portions `6 by means of which it may be mounted to the inner rim 2 around the side and rear portions of the string plate. The string plate comprises generally a rear planar portion 7 and a front portion 8. A pin block is associated with the string plate, usually underlying the front portion 8 of the plate. Between the front and rear portions of the plate there are various ribs indicated at 10, 11, 12, 13 and 14, which not only demark the various sections of the piano from each other but also maintain the front and rear portions of the string plate in association, and so strengthen them that the plate as a whole resists the cumulative tension of the strings. The front portion 15 of the piano case supports a keybed and keyboard as familiar to those skilled in the piano art. It also supports the piano action. For simplicity the keybed and keyboard are not illustrated in the drawings of this application; and no part of the action is shown excepting for the damper elements 16.

In the ordinary construction, the strings pass around hitch pins 17 at the rear portion of the string frame. These hitch pins are metal members press tted in holes formed in the rear portion of the string plate. The pins are bent or inclined rearwardly so that the rear termination of the strings is down against the rear portion 7 of the string plate. In the embodiment illustrated bridges 18 and 19 are attached to the soundboard 3 and the strings pass thereover so that when the strings are set `into vibratory motion by the piano action the vibraory motion will be imparted to the soundboard. In order to prevent the portions of the strings between the bridges and the hitch pins from contacting the plate and, in some instances, in order to terminate these portions of the strings so as to tune them to desired frequencies, string rests or agraffe means 20 are placed upon or fastened to the rear portion of the string plate. Such agraife means are generally triangular in cross section.

The strings extend beyond the bridges 18 and 19 in the forward direction to a second set of agraffe means 21 on the front portion of the string plate. These elements may comprise brass pieces with enlarged heads and threaded Shanks engaged in holes in the string plate. Other forms of front agraife means may be used. In some pianos the strings are caused to contact the edge of a relatively sharp V-shaped configuration on the bottom edge of transverse ribs 22.

Having engaged a forward series of agraffe means 21 the strings proceed in the forward direction to tuning pins 23. The skilled Worker in the art will understand that the strings of a piano are tuned by being selectively tensioned. They are anchored to the various tuning pins 23, and the tension on the strings may be varied by turning these pins with a suitable tuning tool or wrench.

The socalled speaking length of the strings is that portion of the strings extending between the forward agralfe means 21 and the bridges 18 and 19. In FIGURE 1 a group of treble strings is indicated at 24. An intermediate string group is partially indicated at 25, and a series of bass strings is partially indicated at 26.

It will be noted that 'the strings as above described include portions extending rearwardly from the bridges 18 and 19 to the rear agraffe means 20. It is often desirable to locate the rear agraffe means 20 rather carefully so that the vibration frequencies of the rear portions of the strings will bear an approximate harmonic relationship to the vibration frequencies of the speaking length of the strings.

But the tone quality of the piano will be dependent upon a number of factors including those factors which produce a damping action on the strings. There are many such factors and their interaction is extremely complex. Among other things, the nature and construction of the soundboard 3 and of the bridges 18 and 19 are of importance. The bearing or static force of the strings on the bridges is likewise important. Too much bearing force and too little bearing force are both undesirable and will adversely affect the tone.

In accordance with the present invention, and as illustrated in FIGURE 2, instead of using the rearwardly bent hitch pins hereinabove described, use is made of plain cylindrical hitch pins 27. These are hardened steel pins which are press tted in the rear portion 7 of the string plate and extend substantially normal thereto. The skilled worker in the art will understood that where a plurality of strings are used per note, the strings will generally be looped around the hitch pins 27. Where there is only a single string per note, it becomes necessary to anchor an end of the string to the hitch pin. This may be accomplished by forming a loop in the end of the piano string and winding the free end of the string about the body of the string for a short distance. But in either event it will now be evident from a consideration of FIGURE 2 that the engagement of the string 28 with the pin 27 can occur within a range of positions within the length of the free portion of the hitch pin projecting vertically upwardly from the string plate. It is possible to vary the position of engagement by forcibly sliding the engaging portion of the string downwardly or prying it upwardly with respect to the pin 27. This not only varies the downbearing of the string portion 28 against the bridge, but it eliminates entirely the need for the rearward agraffe means 20.

It is also a feature of the invention that the strings may be adjusted as to their downbearing upon the bridge on a string-by-string basis. Since the hitch pins 27 are approximately normal to the plane of the speaking lengths of the strings 28, there will be no tendency for the points of engagement of the strings with the hitch pins to slip either up or down; and although the outer surfaces of the hitch pins are smooth and cylindrical, there will be a very substantial distance along the exposed lengths of the pins where the point of engagement will be found stable.

The points at which the pin-receiving holes are bored in the rear portion 7 of the string plate are chosen in accordance with a predetermined schedule of distances or string lengths so that the vibration frequencies of the duplex portions of the strings extending between the bridge and the hitch pins may be tuned to an approximate harmonic relationship to the vibration frequencies of the speaking length of the strings.

At the front of the piano it is possible to use any of the agraffe means hitherto current in the art to terminate the speaking lengths of the strings. Preferably the forward termination of the strings will be at a height which is nearly t-he same as the height of the bridge. Thus the forward termination will be so located that the strings have a uniform height and hence a predetermined downbearing on the bridge, which downbearing may then be raised or lowered in value solely by adjusting the point of engagement of the strings with the hitch pins 27. This is a substantial simplification both in construction and in adjustment.

FIGURE 3 is an enlarged perspective view of a preferred form of hitch pin which comprises a hollow cylinder 29 having a longitudinal split 30. The pin is made of hardened steel and before installation it has a larger effective diameter than the hole in the string plate into which it is to be driven. As the pin is driven into the opening it is compressed and thus maintains a tight fit in the hole due to the spring-loaded effect created by the split 30.

By utilizing smooth cylindrical hitch pins of the c-haracter disclosed the installation of the pins and their adjustment are materially simplified, as is the adjustment of the bearing of the strings in the bridge. Such pins have been found to conserve the energy of the strings in the duplex section and the tonal characteristics of the instrument are enhanced. The sliding adjustment of the string position minimizes abrading of the strings which occurs in instances wherein it is sought to twist or turn the strings relative to the pins, as where the hitch pins are threaded and the strings retained beneath an enlarged head or in a groove.

The principles of this invention, although most readily and advantageously employed in grand pianos, can be employed in other types of stringed instruments including but without limitation upright pianos, electro-pianos, harpsichords and the like. While reference has been made to a string plate having a front portion and a back portion, it will be understood that these terms are intended to apply to the corresponding structures of other stringed instruments. For this purpose the term front is intended to signify that portion of the string plate or its equivalent which is located adjacent the tuning pins, the term back then referring to the other end of the string plate mounting the hitch pins. Similarly, while the hitch pins are characterized as being smooth and cylindrical, it will be understood that they need not be fully round in cross section but rather are smoothly cylindrical only as to that portion of their circumference against which the strings bear.

Modifications may be made in the invention without departing from the spirit of it.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a musical instrument having a string frame with a front and a back portion, the improvement which comprises pins fitted into holes in the back portion of the string plate and having portions thereof which extend beyond the string plate, said pins consisting of hollow essentially smoothly cylindrical mem-bers each having an opposing pair of longitudinal edges lying in spaced apart relation and displaceable relative to each other to permit dimetral contraction of said pins, and a series of string elements extending between the front and back portions of said plate and engaging said pins intermediate the portions of said pins extending beyond said string plate, the said extending portion of said pins having their axes substantially normal to the string plate and to the direction of extent of the strings, whereby the positions of engagement of said strings with said pins can be adjusted toward and away from said string plate by forcibly sliding the strings with respect to the smoothly cylindrical surfaces of said pins.

2. The structure claimed in claim 1 wherein said pins initially have a larger effective diameter than the holes in which they are inserted, and wherein said pins are press-fitted in said holes.

3. The structure claimed in claim 2 wherein said pins are formed of hardened steel.

`4. In a musical instrument having a string frame with a front and back portion, including a string engaging bridge intermediate the front and back portions of said string frame, the improvement which comprises pins fitted into holes formed in the said back portion of the string frame, the said pins being substantially smoothly cylindrical at least in those portions thereof which extend beyond the string plate and constitute engaging surfaces for the strings, and a series of string elements extending between the front and back portions of said plate and engaging said pins intermediate the portions of said pins extending beyond said string plate, the said extending portions of said pins having their axes substantially normal to said string plate and to the direction of extent of the said strings, whereby the positions of engagement of said strings with said pins can be adjusted toward and away from said string plate by forcibly sliding the strings with respect to the smoothly cylindrical surfaces of said pins, the pin receiving holes in the back portion of said plate being positioned in accordance with a prearranged schedule so that the vibration frequencies of the lengths of the said strings extending between said pins and the said bridge will bear a substantially harmonic relationship to the vibration frequencies of the speaking length of the said strings extending -beyond said -bridge on the other side thereof.

S. The structure claimed in claim 4 wherein said pins consist of hollow smoothly cylindrical members having a longitudinal split therein, the said pins initially having a larger effective diameter than the holes in which they are inserted.

6. The structure claimed in claim 5 wherein the speaking length of said strings extends from said bridge to agraffe means located adjacent the front portion of said string frame and thence to tuning pins projecting from the front portion of said string frame.

7. In a piano having a string frame characterized by a front portion and a back portion, a soundboard and a bridge thereon, hitch pins on the back portion of said string frame and tuning pins mounted with respect to the front portion thereof, the improvement which consists in providing a series of hitch pins of substantially cylindrically conguration mounted in holes in the back portion of said string frame and serving as rear termini for the said strings, the said strings extending freely from the said hitch pins to said bridge and beyond the said bridge in a speaking length to agrafe means adjacent the front portion of said string plate and beyond the said agrafe means to tuning pins, the said hitch pins extending substantially normal to the axial extent of said strings, the said strings being in sliding engagement with the said hitch pins intermediate said string plate and the free ends of said pins and movable axially thereof over a substantial angle relative to said bridge, whereby the downbearing of said strings on said bridge may be adjusted, the pin receiving bores in the back portion of said string frame being positioned in accordance with a. predetermined schedule such that the vibration frequencies of the portions of the strings extending between the said bridge and the said hitch pins bear a substantially harmonic -relationship to the vibration frequencies of the speaking length of said strings extending -between said bridge and said agrafie means.

8. The structure claimed in claim 7 wherein said hitch pins consist of hollow smoothly cylindrical members each having a longitudinal split extending from end to end thereof, and wherein the said pins initially have a larger eective ditameter than the holes in which they are inserted.

References Cited UNITED STATES PATENTS 420,914 2/ 1890 Muller 84-202 903,086 11/ 1908 Heginbothom 84--201 3,332,309 7/1967 Signore SIL-201 1,709,045 4/ 1929 Taylor 84-187 2,240,425 4/ 1941 Sternbergh 85-84 RICHARD B. WILKINSON, Primary Examiner LAWRENCE R. FRANKLIN, Assistant Examiner U.S. Cl. X.R. SLIP-2.02, 204 

